Generally, the traditional warehouse delivery is operated manually, that is, a cart loading with goods is put into the warehouse by a warehouse staff, and then the goods are transported to the corresponding positions of corresponding shelves in sequence. This is time consuming and requires high labor costs, and produces huge potential security problems due to the movement of workers in the warehouse. In addition, the operation becomes more complicated and error-prone when a variety of goods (i.e. the number of stock keeping unit (SKU) is large) are stored in the warehouse.
In order to optimize the delivery operation for warehouse, many attempts have been made to realize automation of warehouse, including the implementation of automatic guided vehicle (AGV), so as to achieve an automatic mode, that is, a robot enters into the storage area, searches for the shelves as required and delivers the products to the sorting station to complete the delivery operation. Existing automatic guided vehicle performs the functions of lifting and lowering using motor and large screw cylinder.
However, such apparatus usually results in the following problems: low electrical efficiency in lifting, leading to limited capability; complicated structures, rendering high manufacturing costs; large screw cylinder being wear-prone, leading to low reliability. During the lifting, lowering and steering, the synchronization of rotations of cart body and large screw cylinder is required, and algorithms for such operation are complicated and less stable. There is provided an improved embodiment: balls are incorporated into the screw cylinder to reduce friction and to improve motor efficiency, however, the manufacturing costs thereof are increased significantly.